1-Azabicyclo[3.2.0]heptan-3,7-dione-2-carboxylic acid

ABSTRACT

Disclosed are the pharmaceutically acceptable salt and ester forms of 1-azabicyclo[3.2.0]heptan-3,7-dione-2-carboxylic acid (I): ##STR1## Such compounds are useful as antibiotics. Also disclosed are processes for the preparation of such compounds, pharmaceutical compositions comprising such compounds and methods of treatment comprising administering such compounds and compositions when an antibiotic effect is indicated.

BACKGROUND OF THE INVENTION

This is a continuation-in-part of U.S. Ser. No. 145,916 filed May 2, 1980, now abandoned, which in turn is a continuation of U.S. Ser. No. 26,978 filed Apr. 4, 1979, now abandoned; which in turn is a continuation of U.S. Ser. no. 843,377 filed Oct. 19, 1977, now abandoned.

This invention relates to the pharmaceutically acceptable salt and ester derivatives of 1-azabicyclo[3.2.0]heptan-3,7-dione-2-carboxylic acid which are useful as antibiotics (I, below): ##STR2## wherein R is a pharmaceutically acceptable salt cation or ester moiety.

The compounds of the present invention (I) are also useful as intermediates in the preparation of the 6-(1'-hydroxyethyl)-3-substituted-1-azabicyclo[3.2.0]hept-2-en-7-one-2-carboxylic acids which are also antibiotics; such compounds are disclosed in U.S. Ser. No. 160,717 filed June 18, 1980, now U.S. Pat. No. 4,318,912, which application is incorporated herein by reference.

This invention also relates to processes for the preparation of the compounds of Structure I; pharmaceutical compositions comprising such compounds; and to methods of treatment comprising administering such compounds and compositions when an antibiotic effect is indicated.

There is a continuing need for new antibiotics. For unfortunately, there is no static effectiveness of any given antibiotic because continued wide scale usage selectively gives rise to resistant strains of pathogens. In addition, the known antibiotics suffer from the disadvantages of being effective only against certain types of microorganisms. Accordingly the search for new antibiotics continues.

Thus, it is an object of the present invention to provide a novel class of antibiotics and intermediates to antibiotics which are useful in animal and human therapy and in inanimate systems. These antibiotics are active against a broad range of pathogens which representatively include both gram positive bacteria such as S. aureus, Strep. pyogenes, B. subtilis, and gram negative bacteria such as E. coli, Proteus morganii, Pseudomonas, Serratia and Klebsiella. Further objects of this invention are to provide chemical processes for the preparation of such antibiotics and their non-toxic pharmaceutically acceptable salts; pharmaceutical compositions comprising such antibiotics; and to provide methods of treatment comprising administering such antibiotics and compositions when an antibiotic effect is indicated.

DETAILED DESCRIPTION OF THE INVENTION

The preparation of the compounds (I) of the present invention may conveniently be summarized by the following reaction diagram: ##STR3##

In words relative to the above reaction diagram starting materials 4 and 8 and the reaction sequence 1→→8 are disclosed in co-pending, commonly assigned U.S. Patent Application Ser. No. 792,071 filed Apr. 28, 1977, now abandoned; this application, as it relates to these starting materials, is incorporated herein by reference. Basically, however, the 4-(2-substituted-vinyl)azetidine-2-one, 4 starting material is prepared by reacting an R¹ -oxybutadiene, 1, with chlorosulfonylisocyanate 2. The reaction is conducted without solvent or may be run in solvent such as diethyl ether, ethyl acetate, chloroform, methylene chloride, or the like, at a temperature of from -78° C. to 25° C. for from a few minutes to 1 hour to provide 3. The radical R¹ is an easily removable acyl blocking group such as an alkanoyl or aralkanoyl which bears no functional group or groups which might interfere with the desired course of reaction (1+2→3→4). Intermediate species 3 is converted to the sulfinamide by reduction which is then hydrolyzed to 4 at pH 6-8. Typically the reaction solution comprising 3 is contacted (5-30 minutes) with an aqueous solution (at 0°-25° C.) of a reducing agent such as sodium sulfite, thiophenol, or the like, at pH 6-8 to provide 4.

The reaction 4→5 is a reduction, and is preferably achieved by hydrogenation in a solvent such as ethyl acetate, ether, dioxane, tetrahydrofuran(THF), ethanol or the like at 0° to 25° C. for from 5 minutes to 2 hours under 1 to 10 atmospheres of hydrogen in the presence of a hydrogenation catalyst such as a platinum metal or oxide thereof such as 10% Pd/C or the like.

The reaction 5→7 establishes, if desired, the N-protecting group R², which preferably is a cyclic ether such as 2-tetrahydropyranyl or a triorganosilyl radical such as trimethylsilyl or t-butyl-dimethylsilyl. Alternatively, R² may be hydrogen. Typically, when the protecting group R² is a triorganosilyl radical, such as t-butyldimethylsilyl, species 5 in a solvent such as DMF, dioxane, THF, Et₂ O or the like in the presence of a base such as triethylamine, imidazole, pyridine, hexamethyl disilazane or the like is contacted with the desired silylating agent such as t-butyldimethylsilylchloride trimethylsilylchloride, isopropyldimethylsilylchloride or the like at a temperature of from -10° to 40° C. for from 10 mins to 8 hours. Suitable reagents for the establishment of R² when R² is cyclic ether such as 2-tetrahydropyranyl, 2-methoxy-2-tetrahydropyranyl, 4-methoxy-4-tetrahydropyranyl or the like are: 2,3-dihydro-4H-pyran, 6-methoxy-2,3-dihydro-4H-pyran, 4-methoxy-5,6-dihydro-2H-pyran and the like. The establishment of such cyclic ether protecting groups is typically conducted in a solvent such as Et₂ O, EtOAc, dioxane, DMF and the like in the presence of an acid, such as toluenesulfonic acid, HCl, or phosphoryl chloride at a temperature of from 0° to 25° C. for from 10 mins to 3 hrs.

The deblocking reaction 6→7 is preferably accomplished by alcoholysis wherein the solvent is a loweralkanol such as methanol, ethanol or the like in the presence of the corresponding alkali metal alkoxide, such as sodium methoxide. Typically, the reaction is conducted for from 5 minutes to 3 hours at a temperature of from -10° to 25° C.

The aldehyde intermediate 8 is prepared by treating 7 with an oxidizing agent such as CrO₃.₂ (pyridine) in CH₂ Cl₂,1:1 mixture of dimethylsulfoxide (DMSO) and acetic anhydride, pyridinium chlorochromate in CH₂ Cl₂, dicyclohexylcarbodiimide in DMSO, methylene chloride or the like at a temperature of from 0°-25° C. for from 5 minutes to 8 hours.

The condensation of the aldehyde to provide species 9 (8→9) is accomplished by treating 8 in a solvent such as Et₂ O (diethyl ether), THF (tetrahydrofuran), DMF (dimethylformamide), HMPA (hexamethylphosphoramide) or the like at a temperature of from -78° C. to 0° C. for from 1 min to 1 hour in the presence of a base such as lithium diisopropylamide, KH, lithium hexamethyldisilazane or the like with an ester of acetic acid (CH₃ CO₂ R³ ; wherein R³ is a readily removable carboxyl protecting group or a pharmaceutically acceptable ester moiety; suitable values for R³ are defined below).

Intermediate ketone species 10 is obtained by oxidation of 9 following the previously described oxidation procedure 7→8. The N-protecting group R² is easily removed by mild acid hydrolysis such as acetic acid in water at a temperature of from 25° to 100° C. for from 1 to 20 hours to provide spcies 11 (10→11).

The diazo species 12 is prepared from 11 by treating 11 in a solvent such as CH₃ CN,CH₂ Cl₂, THF and the like with an azide such as p-carboxy benzenesulfonylazide, toluenesulfonylazide, methanesulfonylazide and the like in the presence of base such as triethylamine, pyridine, C₂ H₅)₂ NH and the like for from 1 to 50 hours at 0° to 25° C.

Cyclization of the diazo compound to provide 13 (12→13) is preferably accomplished by irradiating through a pyrex filter (λ greater than 300 nm) in a solvent such as benzene, CCl₄, Et₂ O, THF or the like at a temperature of from 0° to 25° C. for from 1/2 to 2 hours. Alternatively cyclization of the diazo compound is accomplished by heating in a solvent such as benzene, toluene, THF or the like at a temperature of from 50° to 110° C. for 1-5 hours in the presence of a catalyst such as bis (acetylacetonato) Cu(II) [Cu(AcAc)₂ ], CuSO₄, Cu powder, Rh(OAc)₂, or Pd(OAc)₂. Species 13 may be deblocked if desired to provide I by mild aqueous hydrolysis or hydrogenolysis in the presence of a chosen base to provide I wherein R is an alkali or alkaline earth metal cation.

Species 13 may also be prepared according to the disclosure found in European Patent Application Number 79101307.1 (filed May 1, 1979), publication number 0007973/Al, which is incorporated herein by reference, when the incorporated, disclosed procedure omits the alkylation schemes which establish the 1-hydroxyethyl moiety, Steps 7→8.

It should be noted that the compounds of the present invention exhibit enol-keto tautomerism: ##STR4## For convenience the compounds of the present invention, I, will always be depicted in the keto form.

The compounds of the present invention may also generically be represented by the following structural formula: ##STR5## wherein X' is oxygen, sulfur or NR' (R' is hydrogen or loweralkyl having from 1 to 6 carbon atoms); and R^(3') is representatively selected to provide the pharmaceutically acceptable salt, ester, anhydride (R^(3') is acyl) and amide moieties known in the bicyclic β-lactam antibiotic art.

Identification of the Radical --COX'R^(3')

In the generic representation of the compounds of the present invention (Ia, above), the radical represented by --COX'R^(3') is, inter alia, all carboxyl radicals known to be effective as pharmaceutically acceptable salt, ester, anhydride (R^(3') is acyl, X is O) and amide radicals in the bicyclic β-lactam antibiotic art, such as the cephalosporins and penicillins and the nuclear analogues thereof.

Suitable radicals (R^(3')) include conventional protecting or carboxyl blocking groups. The term "blocking group" as utilized herein is employed in the same manner and in accordance with the teaching of U.S. Pat. No. 3,697,515 which is incorporated herein by reference. Suitable blocking esters thus include those selected from the following list which is representative and not intended to be an exhaustive list of possible ester groups, wherein X'=O and R^(3') is given:

(i) R^(3') =CR^(a) R^(b) R^(c) wherein at least one of R^(a), R^(b) and R^(c) is an electron-donor, e.g., p-methoxyphenyl, 2,4,6-trimethylphenyl, 9-anthryl, methoxy, CH₂ SCH₃, tetrahydrofur-2-yl, tetrahydropyran-2-yl or fur-2-yl. The remaining R^(a), R^(b) and R^(c) groups may be hydrogen or organic substituting groups. Suitable ester groups of this type include p-methoxybenzyloxycarbonyl and 2,4,6-trimethylbenzyloxycarbonyl.

(ii) R^(3') =CR^(a) R^(b) R^(c) wherein at least one of R^(a), R^(b) and R^(c) is an electron-attracting group, e.g., benzoyl, p-nitrophenyl, 4-pyridyl, trichloromethyl, tribromomethyl, iodomethyl, cyanomethyl, ethoxycarbonylmethyl, arylsulphonylmethyl, 2-dimethylsulphoniummethyl, o-nitrophenyl or cyano. Suitable esters of this type include benzoylmethoxycarbonyl, p-nitrobenzyloxycarbonyl, 4-pyridylmethoxycarbonyl, 2,2,2-trichloroethoxycarbonyl and 2,2,2-tribromoethoxycarbonyl.

(iii) R^(3') =CR^(a) R^(b) R^(c) wherein at least two of R^(a), R^(b) and R^(c) are hydrocarbon such as alkyl, e.g., methyl or ethyl, or aryl, e.g., phenyl and the remaining R^(a), R^(b) and R^(c) group, if there is one, is hydrogen. Suitable esters of this type include t-butyloxycarbonyl, t-amyloxycarbonyl, diphenylmethoxycarbonyl and triphenylmethoxycarbonyl.

(iv) R^(3') =R^(d), wherein R^(d) is adamantyl, 2-benzyloxyphenyl, 4-methylthiophenyl or tetrahydropyran-2-yl.

Silyl esters, under this category of blocking groups, may conveniently be prepared from a halosilane or a silazane of the formula: R⁴ ₃ SiX'; R⁴ ₂ SiX'₂ ; R⁴ ₃ Si.NR⁴ ₂ ; R⁴ ₃ Si.NH.COR⁴ ; R⁴ ₃ Si.NH.CO.NH.SiR⁴ ₃ ; R⁴ NH.CO.NH⁴.SiR⁴ ₃ ; or R⁴ C(OSiR⁴ ₃); HN(SiR⁴ ₃)₂ wherein X' is a halogen such as chloro or bromo and the various groups R⁴, which can be the same or different, represent hydrogen atoms or alkyl, e.g., methyl, ethyl, n-propyl, iso-propyl; aryl, e.g., phenyl; or aralkyl, e.g., benzyl groups.

More generally stated, pharmaceutically acceptable carboxyl derivatives of the present invention are those derived by reacting I in its salt form, with alcohols, phenols, mercaptans, thiophenols, acylating reagents and the like. For example, esters and amides of interest are the above-listed starting materials and final products having the following group at the 2-position of the nucleus: --COX'R^(3') wherein X' is oxygen, sulfur, or NR' (R' is H or R^(3')), and R^(3') is alkyl having 1-10 carbon atoms, straight or branched, such as methyl, ethyl, t-butyl, pentyl, decyl and the like; carbonylmethyl, including phenacyl, p-bromophenacyl, p-t-butylphenacyl, acetoxyacetylmethyl, pivaloxyacetylmethyl, carboxymethyl, and its alkyl and aryl esters, o-carboxy-o-isopropyl; aminoalkyl including 2-methylaminoethyl, 2-diethylaminoethyl, 2-acetamidoethyl, phthalimidomethyl, succinimidomethyl; alkoxyalkyl wherein the alkoxy portion has 1-10 and preferably 1-6 carbon atoms; but can be branched, straight or cyclic, and the alkyl portion has 1-6 carbon atoms, such as methoxymethyl, ethoxymethyl, isopropoxymethyl, decyloxymethyl, ethoxypropyl, decyloxypentyl, cyclohexyloxymethyl and the like; alkanoyloxyalkyl wherein the alkanoyloxy portion is straight or branched and has 1-6 carbon atoms and the alkyl portion has 16 carbon atoms, such as acetoxymethyl, pivaloyloxymethyl, acetoxyethyl, propionyloxyethyl, acetoxypropyl, and the like; haloalkyl wherein halo is chloro, bromo, fluoro, or iodo, and the alkyl portion is straight or branched having 1-6 carbon atoms, e.g., 2,2,2-trichloroethyl, trifluoroethyl, 2-bromopropyl diiodomethyl, 2-chloroethyl, 2-bromoethyl, and the like; alkenyl having 1-10 carbon atoms, either straight or branched, e.g., allyl, 2-propenyl, 3-butenyl, 4-butenyl, 4-pentenyl, 2-butenyl, 3-pentenyl, 3-methyl-3-butenyl, metallyl, 1,4-cyclohexadien-1-yl-methyl, and the like alkynyl having 1-10 carbon atoms, either straight or branched e.g., 3-pentenyl, propargyl, ethynyl, 3-butyn-1-yl, and the like; alkanoyl, either straight or branched, having 1-10 carbon atoms, such as pivaloyl, acetyl, propionyl, and the like; aralkyl or heteroaralkyl wherein alkyl has 1-3 carbon atoms, and hetero means 1-4 hetero atoms being selected from the group consisting of O, S, or N, such as benzyl, benzhydryl, and substituted benzyl, benzhydryl, or e.g., benzyl or benzhydryl substituted with 1-3 substituents such as benzyl, phenoxy, halo, loweralkyl, loweralkanoyloxy of 1-5 carbon atoms, lower alkoxy, hydroxy, nitro, blocked carboxy, or combinations thereof, e.g., p-chlorobenzyl, o-nitrobenzyl, 3,5-dinitrobenzyl, p-methoxybenzyl, m-benzoylbenzyl, p-t-butylbenzyl, m-phenoxybenzyl, p-benzoylbenzyl, p-nitrobenzyl, 3,5-dichloro-4-hydroxybenzyl, p-methoxycarbonylbenzyl, p-methoxybenzhydryl, p-carboxybenzyl, the latter being either the free acid, ester or the sodium salt, 2,4,6-trimethylbenzyl, p-pivaloyloxybenzyl, p-t-butoxycarbonyl benzyl, p-methylbenzyl, p-benzoyloxybenzyl, p-acetoxybenzyl, p-2-ethylhexanoylbenzyl, p-ethoxycarbonylbenzyl, p-benzoylthiobenzyl, p-benzamidobenzyl, o-pivaloyloxybenzyl, m-pivaloyloxybenzyl, p-isopropoxybenzyl, p-t-butoxybenzyl, as well as the cyclic analogues thereof, 2,2-dimethyl-5-coumaranmethyl, 5-indanylmethyl, p-trimethylsilylbenzyl, 3,5-bis-t-butoxy-4-hydroxybenzyl; 2-thienylmethyl, 2-furylmethyl, 3-t-butyl-5-isothiazolmethyl, 6-pivaloyloxy-3-pyridazinylethyl, 5-phenylthio-1-tetrazolylmethyl, or the like (the use of the terms lower alkyl or lower alkoxy in this context means 1-4 carbon atoms chain); or phthalidyl; or phenylethyl, 2-(p-methylphenyl)ethyl, and the arylthioalkyl analogues, aryloxyalkyl wherein aryl is preferably a phenyl ring having 0-3 substituents preferably 0 or 1 substituents in the ortho or para positions and alkyl is 1-6 carbon atoms, e.g., (4-methoxy)phenoxymethyl, phenoxymethyl, (4-chloro)phenoxymethyl, (4-nitro)phenoxymethyl, (4-benzyloxy)phenoxymethyl, (4-methyl)phenoxymethyl, (4-benzyloxy)phenoxymethyl, (4-methyl)phenoxymethyl, (2-methoxy)phenoxymethyl, (1-phenoxy)ethyl, (4-amino)phenoxymethyl, (4-methoxy)phenylthiomethyl, (4-chloro)phenylthiomethyl, phenylthioethyl; aryl wherein aryl is phenyl, 5-indanyl, or substituted phenyl having 0-3 substituents, preferably 0 or 1 substituent in the ortho or para position, e.g., (4-methyl)phenyl, (4-hydroxy)phenyl, (4-t-butyl)phenyl, p-nitrophenyl, 3,5-dinitrophenyl, or p-carboxyphenyl, the latter having either the free acid or the sodium salt form; aralkenyl wherein aryl is phenyl and alkenyl has 1-6 carbon atoms, such as 3-phenyl-2-propenyl; aralkoxyalkyl wherein aralkoxy is benzyloxy, and alkyl has 1-3 carbon atoms, such as benzyloxymethyl, (4-nitro)benzyloxymethyl, (4-chloro)benzyloxymethyl; alkylthioalkyl wherein the alkylthio portion has 1-10 and preferably 1-6 carbon atoms, but can be branched, straight or cyclic, and the alkyl portion has 1-6 carbon atoms, such as methylthioethyl, ethylthioethyl, cyclohexylthiomethyl, decylthiobutyl, methylthiopropyl, isopropylthioethyl, methylthiobutyl and the like.

In addition to the esters (and thio esters) listed above, amides are also embraced by the present invention, i.e., wherein X' is the ##STR6## group. Representative of such amides are those wherein R' is selected from the group consisting of hydrogen, methyl, ethyl, phenyl, p-methoxyphenyl, benzyl, carboxymethyl, methylthioethyl, and heteroaryl; also embraced by --COX'R^(3') are anhydrides wherein R^(3') is acyl, for example, benzyloxycarbonyl, ethoxycarbonyl, benzoyl, and pivaloyl.

The most preferred --COX'R^(3') radicals of the present invention are those wherein (relative to Structure Ia above X' is oxygen, sulphur or NR' (R' is selected from the group consisting of hydrogen and lower alkyl); and R^(3') is selected from the group consisting of: loweralkyl, lower alkenyl, such as methallyl, 3-methylbutenyl, 3-butenyl, and the like; methylthioethyl; benzyl and substituted benzyl such as p-t-butylbenzyl, m-phenoxybenzyl, p-pivaloyloxybenzyl, p-nitrobenzyl and the like; pivaloyloxymethyl, 3-phthalidyl and acetoxymethyl, propionyloxymethyl, acetylthiomethyl, pivaloylthiomethyl, allyl, 4-butenyl, 2-butenyl, 3-methyl-2-butenyl, phenacyl, acetoxyacetylmethyl, methoxymethyl, p-acetoxybenzyl, p-pivaloyloxybenzyl, p-isopropoxybenzyl, 5-indanylmethyl, 5-indanyl, benzyloxymethyl, ethylthioethyl, methylthiopropyl, methoxycarbonyloxymethyl, ethoxycarbonyloxymethyl, dimethylaminoacetoxymethyl, crotonolacton-3-yl, and acetamidomethyl.

The preferred salts of the present invention (I, R is a cation) are alkali and alkaline metal salts such as sodium, potassium, and calcium salts and amine salts such as benzhydrylamine, N-benzyl-2-phenethylamine, N,N'-dibenzylethylenediamine, and procaine salts.

The salts of this invention are pharmacologically acceptable non-toxic derivatives which can be used as the active ingredient in suitable unit dosage pharmaceutical forms, also, they may be combined with other drugs to provide compositions having a broad spectrum of activity.

The novel compounds are valuable antibiotics active against various gram-positive and gram-negative bacteria and, accordingly, find utility in human and veterinary medicine. The compounds of this invention can therefore be used as antibacterial drugs for treating infections caused by gram-positive or gram-negative bacteria, for example, against Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Serratia, Salmonella typhosa, Pseudomonas and Bacterium proteus. The antibacterials of the invention may further be utilized as additives to animal feeding stuffs, for preserving foodstuffs and as disinfectants. For example, they may be employed in aqueous compositions in concentrations ranging from 0.1 to 100 parts of antibiotic per million parts of solution in order to destroy and inhibit the growth of harmful bacteria on medical and dental equipment and as bactericies in industrial applications, for example, in waterbased pains and in the white water of paper mills to inhibit the growth of harmful bacteria.

The products of this invention may be used alone or in combination as an active ingredient in any one of a variety of pharmaceutical preparations. These antibiotics and their corresponding salts may be employed in capsule form or as tablets, powders or liquid solutions or as suspensions or elixirs. They may be adminstered orally, intravenously or intramuscularly.

The compositions are preferably presented in a form suitable for absorption by the gastro-intestinal tract. Tablets and capsules for oral administration may be in unit dose presentation form, and may contain conventional excipients such as binding agents, for example, syrup, acacia, gelatin, sorbitol, tragacanth, or polyvinylpyrrolidone; fillers for example, lactose, sugar, maize-starch, calcium phosphate, sorbitol or glycine; lubricants, for example, magnesium stearate, talc, polyethylene glycol, silica; disintegrants, for example, potato starch or acceptable wetting agents such as sodium lauryl sulphate. The tablets may be coated according to methods well known in the art. Oral liquid preparations may be in the form of aqueous or oily suspension, solution, emulsions, syrups, elixirs, etc. or may be presented as a dry product, for reconstitution with water or other suitable vehicles before use. Such liquid preparations may contain conventional additives such as suspending agents, for example, sorbitol syrup, methyl cellulose, glucose/sugar syrup, gelatin, hydroxyethylcellulose, carboxymethyl cellulose, aluminum stearate gel or hydrogenated edible oils, for example almond oil, fractionated coconut oil, oily esters, propylene glycol, or ethyl alcohol; preservatives, for example methyl or propyl p-hydroxybenzoates or sorbic acid. Suppositories will contain conventional suppository bases, e.g. cocoa butter or other glyceride.

Compositions for injection may be presented in unit dose form in ampules, or in multidose containers with an added preservative. The compositions may take such forms as suspensions, solutions, or emulsions in oily or aqueous vehicles, and may contain formulatory agents such as suspending, stabilizing and/or dispersing agents. Alternatively, the active ingredient may be in powder form for reconstitution with a suitable vehicle, e.g. sterile, pyrogen-free water, before use.

The compositions may also be prepared in suitable forms for absorption through the mucous membranes of the nose and throat or bronchial tissues and may conveniently take the form of powder or liquid sprays or inhalants, lozenges, throat paints, etc. For medication of the eyes or ears, the preparations may be presented as individual capsules, in liquid or semi-solid form, or may be used as drops etc. Topical applications may be formulated in hydrophobic or hydrophilic bases as ointments, creams, lotions, paints, powders, etc.

Also, in addition to a carrier, the instant compositions may include other ingredients such as stabilizers, binders, antioxidants, preservatives, lubricators, suspending agents, viscosity agents or flavoring agents and the like. In addition, there may also be included in the composition other active ingredients to provide a broader spectrum of antibiotic activity.

For veterinary medicine the composition may, for example, be formulated as an intramammary preparation in either long or quick-release bases.

The dosage to be administered depends to a large extent upon the condition of the subject being treated and the weight of the host, the route and frequency of administration, the parenteral route being preferred for generalized infections and the oral route for intestinal infections. In general, a daily oral dosage consists of from about 2 to about 600 mg. of active ingredient per kg. of body weight of the subject in one or more applications per day. A preferred daily dosage for adult humans lies in the range of from about 15 to 150 mg. of active ingredient per kg. of body weight.

The instant compositions may be administered in several unit dosage forms as, for example, in solid or liquid orally ingestible dosage form. The compositions per unit dosage, whether liquid or solid may contain from 0.1% to 99% of active material, the preferred range being from about 10-60%. The composition will generally contain from about 15 mg. to about 1500 mg. of the active ingredient; however, in general, it is preferable to employ a dosage amount in the range of from about 100 mg. to 1000 mg. In parenteral administration the unit dosage is usually the pure compound in a slightly acidified sterile water solution or in the form of a soluble powder intended for solution.

The following Examples, illustrate but do not limit the product, process, compositional or method of treatment aspects of the present invention. All temperatures are given in °C.

EXAMPLE 1 Preparation of 4-(2-Acetoxyethyl)-azetidin-2-one ##STR7##

A mixture of 4-(2-acetoxyvinyl)-azetidin-2-one (3.00 g), 10% Pd/C (0.15 g) and ethylacetate(EtOAc)(120 ml) is hydrogenated in a 500 ml glass bomb on a Parr shaker at an initial pressure of 39 psi. After shaking 10 mins (final pressure of 20 psi), the mixture is filtered through a pad of MgSO₄ to remove the catalyst. The filtrate is concentrated in vacuo and the residue stripped with anhydrous benzene to provide 4-(2-acetoxyethyl)-azetidin-2-one (3.098 g) as a clear oil: ir(neat) 3.01, 5.66, 5.75, 7.28, 8.05, and 9.61 cm⁻¹ ; nmr(CDCl₃)δ 1.95 (m, 2), 2.07 (s,3), 2.60 (m, 1), 3.12 (m, 1), 3.70 (m, 1), 4.15 (m, 2), and 6.77 (br s, 1).

EXAMPLE 2 Preparation of N-(t-Butyldimethylsilyl)-4-(2-acetoxyethyl)-azetidin-2-one ##STR8##

Triethylamine (Et₃ N) (2.96 ml, 21.2 mmol) and t-butyldimethylsilyl chloride (3.059 g, 20.3 mmol) are added to an ice-cold stirring solution of 4-(2-acetoxyethyl)-azetidin-2-one (3.098 g, 19.3 mmol) in anhydrous dimethylformamide(DMF) (20 ml). A white precipitate appears immediately. The cooling bath is removed and the mixture is stirred at 25° C. (room temperature) for 5 mins. The mixture is diluted with benzene (200 ml), washed with H₂ O (5×80 ml) and brine, dired with MgSO₄, filtered, and evaporated under reduced pressure to afford N-(t-butyldimethylsilyl)-4-(2-acetoxyethyl)-azetidin-2-one (5.078 g) as an off white solid: ir(neat) 5.75, 8.08, 8.41, 11.92, and 12.18 cm⁻¹ ; nmr (CDCl₃)δ 0.25 (s, 6), 0.98 (s, 9), 1.97 (m, 2), 2.05 (s, 3), 2.67 (dd, 1), 3.20 (dd, 1) 3.62 (m, 1), and 4.12 (t,2); mass spectrum m/e 214 (M⁺ -57) and 172.

EXAMPLE 3 Preparation of N-(t-Butyldimethylsilyl)-4-(2-hydroxyethyl)azetidin-2-one ##STR9##

A solution of N-(t-butyldimethylsilyl)-4-(2-acetoxyethyl)-azetidin-2-one (41.7 g, 0.154 mol) in anhydrous methanol (415 ml) is stirred under a N₂ atmosphere with ice-bath cooling. A solution of sodium methoxide (415 mg, 7.7 mmol) in anhydrous methanol (15 ml) is added and the resulting solution is stirred in the cold for 2 more hrs. Acetic acid (2.2 ml) is then added and the solvents are evaporated in vacuo (i.v.). The residue is taken up EtOAc (300 ml), washed with H₂ O (4×75 ml), 5% NaHCO₃ (75 ml) and brine, dried with MgSO₄ and evaporated i.v. to a clear oil (21.3 g). This material is purified by chromatography on a Baker silica gel column (425 g, packed under EtOAc). After a 100 ml forefraction, 25 ml EtOAc fractions are collected every 2.5 mins. Fractions 41-49 yield starting material and fractions 51-90 afford N-(t-butyldimethylsilyl)-4-(2-hydroxyethyl)-azetidin-2 -one (19.4 g) as a clear oil: ir (neat) 2.88, 5.73, 5.80, 7.52, 7.67, 7.99, 8.40, 11.95, and 12.18 cm⁻¹ ; nmr (CDCl₃)δ 0.25 (s, 6), 0.98 (s, 9), 1.82 (m, 2), 2.67 (dd, 1), 3.17 (dd, 1), 3.67 (t, 2), and 3.67 (m,1); mass spectrum m/e 172.

EXAMPLE 4 Preparation of N-(t-butyldimethylsilyl)-4-(2-oxoethyl)-azetidin-2-one ##STR10##

Anhydrous chromium trioxide (CrO₃) (1.94 g, 19.4 mmol) is added to a solution of anhydrous pyridine (3.07 g, 38.8 mmole) in anhydrous methylene chloride (CH₂ Cl₂) (50 ml). The resulting mixture is stirred at room temperature for 15 mins. A solution of N-(t-butyldimethylsilyl)-4-(2-hydroxyethyl)-azetidin-2-one (0.74 g, 3.23 mmol) in anhydrous CH₂ Cl₂ (5 ml) is added all at once. After stirring at room temperature for 5 mins, the mixture is decanted and the dark, gummy residue is washed with more CH₂ Cl₂. The combined CH₂ Cl₂ supernatant is evaporated i.v. The residue is taken up in diethylether and filtered to remove chromium salts. The ethereal filtrate is washed with 5% NaHCO₃, 5% HCl, 5% NaHCO₃ and brine, dried with MgSO₄, filtered, and evaporated i.v. to yield N-(t-butyldimethylsilyl)-4-(2-oxoethyl)-azetidin-2-one (0.54 g) as an off-white solid: ir(CHCl₃) 5.77, 5.80, 7.36, 7.60, 7.99, 8.50 and 11.95 cm⁻¹ ; nmr (CDCl₃) δ0.23(s, 3), 0.27 (s, 3), 0.98 (s, 9), 2.63 (ddd, 1), 2.65 (dd, 1), 3.07 (ddd, 1), 3.37 (dd), 3.97 (m, 1), and 9.78 (t, 1); mass spectrum m/e 170 and 128.

EXAMPLE 5 Preparation of N-(t-butyldimethylsilyl)-4-(3-benzyloxycarbonyl-2-hydroxypropyl)-azetidin-2-one ##STR11##

To a flame dried, 50 ml, 3-neck flask fitted with a N₂ inlet, magnetic stirrer, addition funnel, and serum cap are added anhydrous tetrahydrofuran (THF) (10.5 ml) and diisopropyl amine (0.579 ml, 4.13 mmol). The solution is cooled in an ice-methanol bath under N₂ and treated with 2.4 N n-butyl lithium in hexane (1.72 ml). After being stirred at -10° for 15 mins, the solution is cooled to -78° and treated dropwise over 9 mins with a solution of benzyl acetate (0.620 g, 4.13 mmol) in anhydrous THF (3.5 ml). After stirring 15 more mins at -78° C., the reaction mixture is treated dropwise over 13 mins with a solution of N-(t-butyldimethylsilyl)-4-(2-oxoethyl)-azetidin-2-one (0.894 g, 3.93 mmol) in anhydrous THF (6 ml). The reaction mixture is stirred at -78° an additional 15 mins and then quenched with 2.5 N HCl (6 ml). EtOAc (100 ml) is added and the organic phase is separated, washed with H₂ O (2×20 ml), 5% NaHCO₃ (20 ml) and brine, dried with MgSO₄, and filtered. The filtrate is evaporated i.v. and the residue stripped with φH (benzene) to yield N-(t-butyldimethylsilyl)-4-(3-benzyloxycarbonyl-2-hydroxypropyl)-azetidin-2-one (1.432 g) as an oil: ir (neat) 2.87, 5.73, 5.79, 7.57, 7.96, 8.39, 11.92, and 12.16 cm⁻¹ ; mass spectrum m/e 362, 320, 278, 170 and 128.

EXAMPLE 6 Preparation of N-(t-butyldimethylsilyl)-4-(3-benzyloxycarbonyl-2-oxopropyl)-azetidin-2-one ##STR12##

Anhydrous CrO₃ (2.274 g, 22.74 mmol) is added to a solution of anhydrous pyridine (3.597 g, 45.48 mmol) in anhydrous CH₂ Cl₂ (60 ml). After stirring at room temperature (25° C.) for 15 mins, the reaction mixture is treated all at once with a solution of N-(t-butyldimethylsilyl)-4-(3-benzyloxycarbonyl-2-hydroxypropyl)-azetidin-2-one (1.432 g, 3.79 mmol) in anhydrous CH₂ Cl₂ (25 ml). The resulting mixture is stirred at 25° C. for 5 mins. The CH₂ Cl₂ layer is decanted from the dark, gummy residue which is triturated with more CH₂ Cl₂. The combined CH₂ Cl₂ phase is evaporated i.v. The residue is triturated with diethylether (Et₂ O) (100 ml) in several portions and the Et₂ O extracts are filtered to remove chromium salts. The ethereal filtrate is washed with 5% NaHCO₃, 1 N HCl, 5% NaHCO₃ and brine, dried with MgSO₄, filtered, and evaporated i.v. to yield N-(t-butyldimethylsilyl)-4-(3-benzyloxycarbonyl)-2-oxopropyl)-azetidin-2-one (1.042 g) as a pale yellow oil: ir (neat) 5.72 (3 poorly resolved peaks), 7.59, 7.98, 8.42, and 11.93 cm⁻¹ ; nmr (CDCl₃) δ0.18 (s, 3), 0.22 (s, 3), 0.97 (s, 9), 2.53 (dd, 1), 2.63 (dd, 1), 3.13 (dd, 1), 3.28 (dd, 1), 3.47 (s, 2), 3.88 (m, 1), 5.17 (s, 2), and 7.33 (s, 5); mass spectrum m/e 360, 318, and 2.76.

EXAMPLE 7 Preparation of 4-(3-benzyloxycarbonyl-2-oxopropyl)-azetidin-2-one ##STR13##

N-(t-butyldimethylsilyl)-4-(3-benzyloxycarbonyl-2-oxopropyl)-azetidin-2-one (302 mg, 0.80 mmol) is dissolved in acetic acid (4.0 ml) and the solution is diluted with H₂ O (2.0 ml). The resulting solution is stirred in a securely stoppered, 10 ml, round-bottom flask in an oil bath maintained at 73° C. for 7 hrs. After cooling to room temperature, the reaction mixture is diluted with EtOAc and toluene and evaporated i.v. The residue is stripped twice with toluene to yield a yellow oil (220 mg). The crude product is chromtographed on Baker silica gel (8.8 g, packed under EtOAc). The column is eluted with EtOAc; 3 ml fractions being collected every 2.25 mins. Fractions 14-30 are combined and evaporated i.v. to provide 4-(3-benzyloxycarbonyl-2-oxopropyl)-azetidin-2-one (114 mg) as a clear oil: ir (neat) 3.04, 5.68, 5.72 and 5.83 cm⁻¹ ; nmr (CDCl₃) δ2.52 (ddd, 1), 2.67 (dd, 1), 3.02 (dd, 1), 3.12 (ddd, 1), 3.48 (s, 2), 3.88 (m, 1), 5.18 (s, 2), 6.17 (m, 1), and 7.37 (s, 5); mass spectrum m/e 261 (M⁺), 233, 219, 192, 127 and 91.

EXAMPLE 8 Preparation of 4-(3-benzyloxycarbonyl-3-diazo-2-oxopropyl)-azetidin-2-one ##STR14##

Freshly recrystallized p-carboxy benzene sulfonylazide (241 mg, 1.06 mmol) is added to a solution of 4-(3-benzyloxycarbonyl-2-oxopropyl)-azetidin-2-one (276 mg, 1.06 mmol) in anhydrous acetonitrile (6.6 ml). The resulting suspension is cooled in an ice-bath and stirred while Et₃ N (443 μl, 3.18 mmol) is added. The resulting yellow solution is stirred at room temperature. A precipitate forms quickly. After 90 mins, the mixture is diluted with EtOAc (50 ml) and filtered. The filtrate is washed with H₂ O (2×10 ml), 0.5 N NaOH (2×10 ml), H₂ O (4×10 ml) and brine, dried with MgSO₄, filtered, and evaporated i.v. to an off-white solid (273 mg). This is triturated with Et₂ O to provide 4-(3-benzyloxycarbonyl-3-diazo-2-oxopropyl)-azetidin-2-one (227 mg) as a cream colored powder: ir (film from CHCl₃) 3.0, 4.65, 5.66, 5.82, 6.05, 7.21, 7.70 and 8.23 cm⁻ 1 ; nmr (CDCl₃) δ2.63 (ddd, 1), 2.97 (dd, 1), 3.15 (ddd, 1), 3.40 (dd, 1), 3.98 (m, 1), 5.27 (s, 2), 6.13 (m, 1), and 7.38 (s, 5); mass spectrum m/e 259, 245, 231, and 218.

EXAMPLE 9 Preparation of benzyl 1-azabicyclo[3.2.0]heptan-3,7-dione-2-carboxylate ##STR15##

A solution of 4-(3-benzyloxycarbonyl-3-diazo-2-oxopropyl)-azetidin-2-one (20 mg) in anhydrous benzene (5 ml) is irradiated for 60 mins at room temperature using a Hanovia 450 W medium-pressure mercury lamp and a Pyrex filter. Dry N₂ is bubbled through the solution prior to and during the photolysis. Evaporation of the solvent in vacuo gives an oil (17 mg) which is purified by chromatography on a 250μ×20×20 cm silica gel GF plate using 3:1 φH-EtOAc as developing solvent. The band at Rf 0.3 is removed and eluted with EtoOAc to give a clear oil (2.4 mg). This material is further purified by tlc on a 250μ×7.5×8.5 cm silica gel GF plate. The cleanly resolved band at Rf 0.29 is removed and eluted with EtOAc to give benzyl 1-azabicyclo[3.2.0]heptan-3,7-dione-2-carboxylate (0.7 mg) as a clear oil: ir (CCl₄) 1783, 1773, and 1744 cm⁻¹ ; ir (CHCl₃) 1767, 1741 cm⁻¹ ; uv (Cy) 215 nm; nmr (CDCl₃) δ2.36 (dd, J=8 and 18.5, 1), 2.90 (dd, J=6 and 18.5, 1), 2.92 (dd, J=2 and 16, 1), 3.63 (dd, J=5 and 16, 1), 4.11 (m, 1), 4.71 (s, 1), 5.19 (s, 2) and 7.33 (s, 5); mass spectrum m/e 259 (M⁺), 231 (M⁺ -28), 217 (M⁺ -42), 203, 187, 186, 168 (M⁺ -91), 124, and 91; high resolution mass spectrum m/e 259.0842 (C₁₄ H₁₃ NO₄).

EXAMPLE 10 Preparation of sodium 1-azabicyclo[3.2.0]heptan-3,7-dione-2-carboxylate ##STR16##

Benzyl 1-azabicyclo[3.2.0]heptan-3,7-dione-2-carboxylate (25 mg) is hydrogenated at 40 psi for 1 hr in dioxane (2 ml) containing ethanol (0.5 ml), H₂ O (0.5 ml), NaHCO₃ (8.1 mg) and 10% Pd/C (10 mg). The mixture is filtered to remove the catalyst which is washed with more H₂ O (2.5 ml). The combined filtrate and washing is extracted with EtOAc (3×2 ml), concentrated under reduced pressure, and lyophilized to provide sodium 1-azabicyclo[3.2.0]heptan-3,7-dione-2-carboxylate.

EXAMPLE 11 Preparation of Pivaloyloxymethyl 1-azabicyclo[3.2.0]heptan-3,7-dione-2-carboxylate ##STR17##

To a stirring suspension of sodium 1-azabicyclo[3.2.0]heptan-3,7-dione-2-carboxylate (20 mg) in anhydrous hexamethylphosphoramide (0.5 ml) is added bromomethyl pivalate (35 mg). The resulting mixture is stirred at room temperature for 2 hrs, then diluted with benzene (5 ml) and washed thoroughly with H₂ O (5×2 ml) and brine. The benzene solution is dried with MgSO₄, filtered, and concentrated under reduced pressure. Preparative tlc of the residue on a silica gel GF plate provides pivaloyloxymethyl 1-azabicyclo[3.2.0]heptan-3,7-dione-2-carboxylate.

EXAMPLE 12 Benzyl 1-azabicyclo[3.2.0]heptan-3,7-dione-2-carboxlate ##STR18##

A mixture of 4-(3-benzyloxycarbonyl-3-diazo-2-oxopropyl)-azetidin-2-one (718 mg. 25 mMol), rhodium (II) acetate (5 mg) and anhydrous benzene (50 ml) is deoxygenated by bubbling nitrogen through it for 45 minutes. The mixture is then stirred and heated in an oil bath maintained at 80° C. for 70 minutes. After cooling to room temperature, the mixture is filtered and the filtrate is evaporated under vacuum to an oil. Crystallization from ethyl acetate (5 ml)-diethylether (20 ml) provides benzyl 1-azabicyclo[3.2.0]heptan-3,7-dione-2-carboxylate (502 mg, 77% yield) as small, white prisms: mp 100°-102°; IR (CH₂ Cl₂) 1770; 1741 cm⁻¹ ; UV (dioxane) 220 nm; NMR (CDCl₃, 300 MHz) δ2.43 (dd, 1, J=8 and 19, H4a), 2.94 (dd, 1, J=6.5 and 19, H4b), 2.99 (dd, 1, J=2 and 16, H6B), 3.63 (dd, 1, J=5 and 16, H6α), 4.18 (m, 1, H5), 4.76 (S, 1, H2), 5.23 (S, 2, CH₂ φ), and 7.40 (S, 5, ArH); MS m/e 259 (M⁺), 231 (M⁺ -28), 217 (M⁺ -42), 203, 187, 186, (M⁺ -91), 124, and 91.

Anal. Calculated for C₁₄ H₁₃ NO₄ : C, 64.86; H, 5.05; N, 5.40. Found: C, 64.92; H, 5.01; N, 5.11.

EXAMPLE 13 Dicyclohexylammonium 1-azabicyclo[3.2.0]heptan-3,7-dione-2-carboxylate ##STR19##

A solution of benzyl 1-azabicyclo[3.2.0]heptan-3,7-dione-2-carboxylate (25.9 mg, 0.1 mMol) in dioxane (1.5 ml) is added to a mixture of 10% palladium on charcoal (5 mg) and dioxane (1.0 ml) which has been equilibrated under an atmosphere of hydrogen for 10 minutes. The resulting mixture is stirred under 1 atmosphere of hydrogen at room temperature for 30 mins., during which time 2.6 ml of hydrogen are absorbed. The mixture is filtered and the catalyst is washed with more dioxane (0.5 ml). The filtrate, which contains 1-azabicyclo[3.2.0]heptan-3,7-dione-2-carboxylic acid, is divided into two equal 1.5 ml portions.

One portion of the dioxane filtrate is treated with a solution of dicyclohexylamine (9.1 mg, 0.05 mMol) in dioxane. The solvent is removed under vacuum and the residue is triturated with diethyl ether to yield dicyclohexylammonium 1-azabicyclo[3.2.0]heptan-3,7-dione-2-carboxylate as a white powder: IR (Nujol) 1764, 1637 cm⁻¹ ; NMR (D₂ O) δ1.1-2.2 (m, --CH₂ CH₂ CH₂ CH₂ CH₂ --), 2.64 (dd,J=7.8 and 19.0, H4a), 2.89 (dd, J=7.9 and 19.0, H4b), 3.08 (dd, J=2 and 16.6, H6β), 3.26 (m, N--CH), 3.61 (dd, J=4.7 and 16.6, H6α), 4.17 (m, H5), and 4.8 (br s, HOD, obscures H2 resonance).

EXAMPLE 14 Benzyl 3-(p-toluenesulfonyloxy)-1-azabicyclo[3.2.0]hept-2-en-7-one-2-carboxylate ##STR20##

p-Toluenesulfonic anhydride (326 mg, 1 mμol) and N,N-diisopropylethylamine (192 μl, 1.1 mμol) are added to an ice-cold, stirring solution of benzyl 1-azabicyclo[3.2.0]heptan-3,7-dione-2-carboxylate (259 mg, 1 mμol) in anhydrous methylene chloride (10 ml). The resulting solution is stirred in the cold and under a nitrogen atmosphere for 2.5 hours. The solution is diluted with methylene chloride (20 ml), washed with water (10 ml). 1 M pH3 phosphate buffer (10 ml) and 5% aqueous sodium bicarbonate (2×10 ml) dried with magnesium sulfate, filtered, and evaporated under vacuum to a semi-solid. This material is triturated with ice-cold ethyl acetate (2×2 ml) and diethyl ether (2×5 ml) to provide benzyl 3-(p-toluenesulfonyloxy)-1-azabicyclo[3.2.0]hept-2-en-7-one-2-carboxylate (276 mg, 67%) as a white powder. Recrystallization from methylene chloridediethyl ether gives analytically pure product as small white needles: mp 103°-105°; IR (CH₂ Cl₂) 1786, 1723, 1382, and 1190 cm⁻¹ ; NMR (CDCl₃) 8 2.44 (s,3,ArCH₃) 3.03 (dd,1,J=3.0 and 17.0,H6β), 3.16 (dd,1,J=8.5 and 18.7,H4a), 3.32 (dd,1,J=10.0 and 18.7,H4b), 3.55 (dd,1,J=5.5 and 17.0, H6α), 4.21 (m,1,H5), 5.14 (ABq,2,J=12,CH₂ Ar), 7.35 (S,5,ArHN, 7.26 and 7.75 (two d's,4,J=9,ArH); UV(dioxane) 283 (ε6600) and 277 (ε6500) nm.

Anal., Calculated for C₂₁ H₁₉ NO₆ S: C, 61.01; H, 4.63; N, 3.39. Found: C, 59.94; H, 4.47; N, 3.26.

EXAMPLE 15 Benzyl 3-(p-nitrobenzenesulfonyloxy)-1-azabicyclo[3.2.0]hept-2-en-7-one-2-carboxylate ##STR21##

An ice-cold solution of benzyl 1-azabicyclo[3.2.0]heptan-3,7-dione-2-carboxylate (20 mg, 0.077 mmol) in methylene chloride (2 ml) is treated with p-nitrobenzenesulfonic anhydride (37.3 mg, 0.096 mmol) and N,N-diisopropylethylamine (18.3 μl, 0.015 mmol). After stirring in the cold for 20 minutes, the solution is diluted with cold methylene chloride (1 ml) and cold 0.1 M pH 7 phosphate buffer (2 ml) and shaken. The organic phase is separated, washed with cold 0.1 M pH 7 phosphate buffer (2×2 ml), water and brine, dried with magnesium sulfate, and filtered. The filtrate is diluted with cold methanol (0.5 ml) and quickly evaporated under vacuum to give a solid. The crude product is triturated with cold methanol and dried under vacuum to provide benzyl 3-(p-nitrobenzenesulfonyloxy)-1-azabicyclo[3.2.0]hept-2-en-7-one-2-carboxylate (26 mg) as a white solid: mp 86°-88°; IR (CH₂ Cl₂) 1794, 1723, 1521, and 1344 cm⁻¹ ; UV (CHCl₃) 257 (ε10,600) and 280 (ε7,600) nm; NMR (CDCl₃) δ3.08 (dd, 1, J=3.6 and 17, H6β), 3.25 (dd, 1, J=8.8 and 18, H3a), 3.35 (dd, 1, J=9.8 and 18, H4b), 3.59 (dd, 1, J=5.4 and 17, H6α), 4.26(m,1,H5), 5.10 (ABq, 2, J=21.2, CH₂ φ), 7.32 (s, 5, C₆ H₅), 8.03 and 8.22 (two d's, 4, J=9.3, NO₂ C₆ H₄).

Preparation of p-nitrobenzene sulfonic anhydride

A mixture of p-nitrobenzenesulfonic acid (20 g), phosphorous pentoxide (50 g) and 1,2-dichloroethylene (100 ml) is heated at reflux for 4 days. The hot supernatant is decanted from the gummy residue and allowed to cool to room temperature. The resulting crystalline precipitate of p-nitrobenzenesulfonic anhydride (1.5 g) is collected, washed with anhydrous diethylether, and dried under vacuum. The gummy residue is twice more refluxed overnight with 100 ml portions of dichloroethylene and worked up as above to provide additional p-nitrobenzenesulfonic anhydride (4.0 g); mp 171°-172°.

EXAMPLE 16 Benzyl 3-diphenylphosphoryl-1-azabicyclo[3.2.0]hept-2-en-7-one-2-carboxylate ##STR22##

An ice-cold, stirring solution of benzyl 1-azabicyclo[3.2.0]heptan-3,7-dione-2-carboxylate (13 mg, 0.05 mMol), 4-dimethylamino pyridine (1.2 mg, 0.01 mMol) and N,N-diisopropylethylamine (12.2 μl, 0.07 mMol) in anhydrous acetonitrile (0.5 ml) is treated with diphenyl chlorophosphate (12.4 μl, 0.06 mMol). The resulting solution is stirred in the cold and under a nitrogen atmosphere for 2 hours, then diluted with methylene chloride (5 ml), washed with water (2 ml), 0.1 M pH 7 phosphate buffer (2 ml) and brine, dried over magnesium sulfate, and filtered. Evaporation of the filtrate under vacuum leaves crude benzyl 3-diphenylphosphoryl-1-azabicyclo[3.2.0]-hept-2-en-7-one-2-carboxylate (22 mg) as an oil: UV (dioxane) 281 nm; NMR(CDCl₃) δ2.90 (dd,1,J=3 and 17, H6β), 3.17(m,2,H4a and H4b), 3.52 (dd, 1,J=5.5 and 17, H6α), 4.13(m,1,H5), 5.28(S,2,CH₂ φ), and 7.30(m,15,ArH).

EXAMPLE 17 N-(t-Butyldimethylsilyl)-4-[3-(p-nitrobenzyloxycarbonyl)-2-hydroxypropyl]-azetidin-2-one ##STR23##

A mixture of crude N-(t-butyldimethylsilyl)-4-(3-benzyloxycarbonyl-2-hydroxypropyl)-azetidin-2-one (11.33 g, 30 mmol), ethanol (300 ml) and 10% palladium on charcoal (1.13 g) is hydrogenated at 50 psi for 1 hour. The mixture is filtered and the filtrate is treated with water (150 ml) containing sodium bicarbonate (2.52 g, 30 mmol) and concentrated under vacuum to ca 100 ml. The aqueous concentrate is washed with ethyl acetate (2×100 ml) and lyophilized to provide the sodium carboxylate (7.70 g) as a white powder.

The sodium salt and p-nitrobenzyl bromide (6.48 g, 30 mmol) are dissolved in anhydrous dimethyl formamide (150 ml) under a nitrogen atmosphere. After standing for 1 hour at room temperature, the solution is evaporated under vacuum to a semi-solid. The residue is taken up in ethyl acetate (200 ml), washed with water (2×200 ml) and brine, dried over magnesium sulfate, filtered, and evaporated under vacuum. The residual yellow oil is chromatographed on silica gel (250 g) using 1:1 toluene-ethyl acetate as eluting solvent to provide N-(t-butyldimethylsilyl)-4-[3-(p-nitrobenzyloxycarbonyl)-2-hydroxypropyl]-azetidin-2-one (8.92 g, 70%) as an oil which solidified on standing: IR (CH₂ Cl₂) 3585, 1733, 1527, and 1350 cm⁻¹ ; NMR(CDCl₃) δ0.22 (s,3,CH₃), 0.25 (s,3,CH₃), 0.93 (s,9,C(CH₃)₃), 1.16-2.33 (m,2,CH--CH₂ --CH), 2.40-3.47 (m,3,OH and H3α and H3β), 2.55 (d,2,J=6, CH₂ CO₂), 3.50-4.33 (m,2,H4 and CH--OH), 5.30 (s,2,CH₂ Ar), and 7.55, 8.27 (two d's,4,J=8.5, ArH).

EXAMPLE 18 N-(t-Butyldimethylsilyl)-4-[3-(p-nitrobenzyloxycarbonyl)-2-hydroxypropyl]-azetidin-2-one ##STR24##

A mixture of crude N-(t-butyldimethylsilyl)-4-(3-benzyloxycarbonyl-2-Hydroxypropyl)-azetidin-2-one (13.46 g, 35.6 mmol), 10% palladium on charcoal, and ethanol (200 ml) is hydrogenated at 40 psi for 30 mins. The mixture is filtered and the filtrate is evaporated under vacuum and stripped with toluene to give N-(t-butyldimethylsilyl)-4-(3-carboxy-2-hydroxypropyl)-azetidin-2-one (9.51 g) as an off-white solid: IR (neat film from Me₂ CO) 3200 (br), 1735, and 1700 (shifts to 1590 with Et₃ N) cm⁻¹ ; NMR (Me₂ CO-d₆) δ0.25 (s,6,2CH₃), 0.98 (s,9,C(CH₃)₃) 1.17-2.33 (m,2,CH--C CH₂ --CH), 2.50 (d,2,J=6.5, CH₂ CO₂), 2.50-3.40 (m,2,H3 and H3β), 3.97 (m,2,H4 and CHOH); MS on bistrimethylsilyl derivative m/e 431 (M+), 416 (M+-57) and 332 (374-42).

The crude carboxylic acid is suspended in anhydrous acetonitrite (150 ml) and treated with p-nitrobenzyl bromide (7.56 g, 35 mμol) and triethylamine (4.9 ml, 35 mμol). The resulting solution is kept at room temperature for 2 days and then in a refrigerator for 3 days. The reddish orange solution is evaporated under vacuum and the residue shaken with ethyl acetate (100 ml, 2×50 ml) and filtered to remove triethylammonium bromide. The ethyl acetate filtrate is washed with water (3×100 ml) and brine, dried with magnesium sulfate, filtered, and evaporated under vacuum to an amber oil (13.62 g). Crystallization from diethyl ether affords N-(t-butyldimethylsilyl)-4-[3-(p-nitrobenzyloxycarbonyl)-2-hydroxypropyl]-azetidin-2-one (6.84 g) as an off-white powder. Chromatography of the mother liquors on a silica gel column using 1:1 toluene-ethyl acetate as eluting solvent affords addition product (3.14 g) as an oil which solidifies.

EXAMPLE 19 N-(t-Butyldimethylsilyl)-4-[3-(p-nitrobenzyloxycarbonyl)-2-oxopropyl]-azetidin-2-one ##STR25##

Anhydrous chromium trioxide (16.88 g 169 mmol) is added to a solution of anhydrous pyridine (27.3 ml, 338 mmol) in anhydrous methylene chloride (470 ml). The resulting mixture is stirred at room temperature for 30 minutes and then treated with a solution of N-(t-butyldimethylsilyl)-4-[3-(p-nitrobenzyloxycarbonyl)-2-hydroxypropyl]-azetidin-2-one (8.92 g, 21.1 mmol) in methylene chloride (80 ml). The reaction mixture is stirred an additional 15 minutes at room temperature and then treated with 2-propanol (6.75 ml). The methylene chloride phase is decanted from the dark, tary residue and evaporated under vacuum. The residue from this operation is triturated with diethyl ether (350 ml) and filtered through a pad of magnesium sulfate which is washed with additional ether (150 ml). The ethereal filtrate is washed with water (200 ml), 5% aqueous sodium bicarbonate (200 ml) and brine, dried with magnesium sulfate, filtered, evaporated under vacuum, and stripped with toluene to afford the crude product (5.99 g) as an amber oil. Chromatigraphy on a silica gel column using 3:2 petroleum ether-ethyl acetate as eluting solvent yields N-(t-butyldimethylsilyl)-4-[3-(p-nitrobenzyloxycarbonyl)--2-oxopropyl]-azetidin-2-one (5.17 g, 58%) as a pale yellow, viscous oil which solidifies. Trituration with diethyl ether gives the product as small, white crystals: mp 65°-66.5°, IR (CH₂ Cl₂) 1732, 1522, and 1350 cm⁻¹, NMR (CDCl₃) δ0.20 (s,3,CH₃), 0.23 (s,3,CH₃), 0.93 (s,9,C(CH₃)₃), 2.58 (dd,1,J=2.7 and 15.7, H3β), 2.72 (dd,1, J=9.4 and 18.2, CH₂ COCH₂ CO₂), 3.19 (dd,1,J=4.0 and 18.2, CH₂ COCH₂ CO₂), 3.35 (dd,1,J=5.3 and 15.7,H3β), 3.55 (s,2, COCH₂ CO₂), 3.90 (m,1,H4), 5.30 (s,2,CH₂ Ar), 7.55 and 8.25 (two d, 4,J=8.5, ArH); MS m/e 405 (M⁺ -15), 363 (M⁺ -57), 321 (363-42) and 136.

Anal. Calculated for C₂₀ H₂₈ N₂ O₆ Si: C,57.12; H,6.71; N,6.66. Found: C,57.28; H,6.75; N,6.60.

EXAMPLE 20 4-[3-(p-nitrobenzyloxycarbonyl)-2-oxopropyl]azetidin-2-one ##STR26##

A solution of N-(t-butyldimethylsilyl)-4-[3-(p-nitrobenzyloxycarbonyl)-2-oxopropyl]-azetidin-2-one (5.17 g, 12.3 mMol) in methanol (55 ml) is treated with 1 N hydrochloric acid (6.2 ml) and then kept at room temperature for 200 mins. The solution is treated with 1 M dipotassium hydrogenphosphate (6.2 ml) and concentrated under vacuum. The residue is taken up in ethyl acetate (100 ml), washed with brine, dried over magnesium sulfate, filtered, and evaporated under vacuum. Triturating the resulting oil with diethyl ether yields 4-[3-(p-nitrobenzyloxycarbonyl)-2-oxopropyl]-azetidin-2-one (3.42 g, 91%) as an off-white powder: mp 50°-52°; IR (CH₂ Cl₂) 3416, 1767, 1723, 1528, and 1352 cm⁻¹ ; NMR (CDCl₃) ε2.60 (ddd,1,J=1,2.7, and 15.1,H3β), 2.77 (dd,1,J=8.4 and 18.2, CHCH₂ CO), 3.13 (dd,1,J=5.1 and 18.2, CHCH₂ CO), 3.20 (ddd,1,J=2,4, 5.0, and 15.1, H3α), 3.57 (s,2,COCH₂ CO₂), 3.98 (m,1,H4); 5.27 (s,2,CH₂ Ar), 6.28 (br,s,1,NH), 7.53 and 8.23 (two d's,4,J=8.5, ArH); mass spectrum m/e 306(M+), 264(M+-42), 237, 153, 125, 111, and 136.

EXAMPLE 21 4-[3-(p-Nitrobenzylrycarbonyl)-3-diazo-2-oxopropyl]-azetidin-2-one ##STR27##

p-Carboxybenzyenesulfonylazide (2.67 g, 11.8 mMol) and triethylamine (4.68 ml, 33.6 mMol) are added to an ice-cold, stirring solution of 4-[3-(p-nitrobenzyloxycarbonyl)-2-oxopropyl]-azetidin-2-one (3.42 g, 11.2 mMol) in anhydrous acetonitrile (70 ml). The resulting mixture is stirred in the cold for 10 minutes and at room temperature for 60 minutes. The mixture is diluted with ethyl acetate (200 ml) and filtered. The filtrate is washed with water (2×100 ml), 1 M pH 3 phosphate buffer (50 ml), 0.1 M pH 7 phosphate buffer (100 ml), and brine, dried over magnesium sulfate, filtered, and evaporated under vacuum to a yellow foam (3.75 g). The crude product is taken up in methylene chloride (ca. 10 ml), heated briefly with activated charcoal, and filtered through a pad of magnesium sulfate. The filtrate is diluted with diethyl ether (ca. 40 ml) and scratched to yield a precipitate. The precipitate is collected, washed with ether, and dried under vacuum to provide 4-[3-(p-nitrobenzyloxycarbonyl)-3-diazo-2-oxopropyl]-azetidin-2-one (3.29 g, 88%) as a pale yellow powder: mp 114.5°-116.5°; IR (CH₂ Cl₂) 3413, 2142, 1767, 1724, 1657, 1530, and 1352 cm⁻¹ ; NMR (CDCl₃) δ2.68 (ddd,1,J=1.2, 2.7, and 14.8, H3β), 3.02 (dd,1,J=8.4 and 18.0, CHCH₂ CO), 3.22 (ddd,1,J=2.4, 4.8, and 14.8, H3α); 343 (dd,1,J=4.6 and 18.0, CHCH₂ CO), 4.00 (m,1,H4), 5.38 (s,2,CH₂ Ar), 6.30 (brs,1,NH), 7.57 and 8.27 (two d's,4, J=8.5, ArH); mass spectrum m/e 332(M+), 304(M+-28), 290(M+-42), 262, and 263.

Anal., calculated for C₁₄ H₁₂ N₄ O₆ : C,50.61; H,3.64; N,16.86. Found: C,50.34; H,3.42; N,16.72.

EXAMPLE 22 P-Nitrobenzyl 1-azabicyclo[3.2.0]heptan-3,7-dione-2-carboxylate ##STR28##

A suspension of 4-[3-(p-nitrobenzylocycarbonyl)-3-diazo-2-oxopropyl]-azetidin-2-one (2.93 g) and rhodium (II) acetate (15 mg) in anhydrous toluene (300 ml) is degassed by bubbling nitrogen through it for 60 minutes. The mixture is then stirred and heated in an oil bath maintained at 80° C. After a few minutes, the diazo compound dissolves and gas evolution commences. The mixture is heated at 80° C. for 100 minutes, then allowed to stand at room temperature for 30 mins. before filtering through a pad of celite. The filtrate is evaporated under vacuum to an oily residue which is triturated with diethyl ether to afford p-nitrobenzyl 1-azabicyclo[3.2.0]heptan-3,7-dione-2-carboxylate (2.53 g, 94%) as an off-white powder. Recrystallization from ether provides analytically pure product: mp 127°-128°; IR (CH₂ Cl₂) 1776, 1753, 1529, and 1352 cm⁻¹ ; NMR (CDCl₃) δ2.47 (dd,1,J=8.2 and 18.8, H4a), 2.98 (dd, 1,J=6.8 and 18.8, H4b), 3.00 (dd,1,J=2.0 and 12.0, H6β), 3.70 (dd,1,J=4.8 and 12.0, H6 β), 4.20 (m,1,H5), 4.80 (s,1,H2), 5.32 (s,2,CH₂ Ar), 7.57 and 8.25 (two d's,4, J=8, ArH); mass spectrum m/e 304(M+), 276(M+-28), 262 (M+-42), and 168(M+-136).

Anal., calculated for C₁₄ H₁₂ N₂ O₆ : C,55.27; H,3.98; N,9.21. Found: C,55.06; H,4.03; N,8.99.

EXAMPLE 23 P-Nitrobenzyl 3-(p-toluenesulfonyloxy)-1-azabicyclo[3.2.0]hept-2-en-7-one-2-carboxylate ##STR29##

p-toluenesulfonic anhydride (520 mg, 1.59 mmol) and N,N-diisopropylethylamine (300 μl, 1.72 mmol) are added to an ice-cold, stirring solution of p-nitrobenzyl 1-azabicyclo3.2.0]heptan-3,7-dione-2-carboxylate (484 mg, 1.59 mmol) in anhydrous methylene chloride (17 ml). The resulting solution is stirred in the cold for 2 hours, then diluted with more methylene chloride, washed with water, 1μ ph 3.4 phosphate buffer and saturated aqueous sodium bicarbonate, dried with magnesium sulfate, filtered, and evaporated under vacuum. Addition of cold ethyl acetate and a few seed crystals to the oily residue induces crystallization. The product is collected, washed with cold ethyl acetate, and dried under vacuum to afford p-nitrobenzyl 3-(p-toluenesulfonyloxy)-1-azabicyclo[3.2.0]hept-2-en-7-one-2-carboxylate (446 mg, 61%) as off-white crystals: mp 99°-102° (dec.); IR (neat) 1790, 1725, 1521, 1345, and 1172 cm⁻¹ ; UV (CH₂ Cl₂) 272 nm; NMR (CDCl₃) δ 2.40 (s,3,ArCH₃), 3.06 (dd,1,J=3.0 and 17.2, H6β), 3.16 (dd,1, J=9.0 and 9.0,H4a), 3.31 (dd,1,J=9.0 and 10.0, H4b), 3.59 (dd,1,J=5.8 and 17.2, H6α), 4.24 (m,1,,H5), 5.20 and 5.32 (ABq,2,J=14.0,CH₂ Ar), 7.32 and 7.77 (two d's,4,J=8.0, p-MeC₆ H₄), 7.51 and 8.19 (two d's,4,J=8.0,p-NO₂ C₆ H₄).

EXAMPLE 24 Benzyl 3-methoxy-1-azabicyclo[3.2.0]hept-2-en-7-one-2-carboxylate ##STR30##

A solution of benzyl 1-azabicyclo[3.2.0]heptan-3,7-dione-2-carboxylate (25.9 mg, 0.1 mMol) in anhydrous hexamethylphosphoramide (1.0 ml) is cooled in an ice-bath and stirred under a nitrogen atmosphere. Dimethyl sulfate (11.4 μl, 0.12 mMol) and 57% sodium hydride in mineral oil (5.0 mg, 0.12 mMol) are added to the solution. The cooling bath is removed and the resulting mixture is stirred at room temperature for 60 minutes. The mixture is diluted with ethyl acetate (10 ml) and water (20 ml), shaken, and the layers separated. The organic layer is washed with water (3×5 ml) and brine, dried with magnesium sulfate, diluted with toluene (10 ml), and evaporated under vacuum to an oil. This material is chromatographed on a 0.25 mm×10×20 cm silica gel GF plate using 3:1 toluene-ethyl acetate as developing solvent. The major UV visible band at R_(f) 0.1 was removed and eluted with ethyl acetate to provide benzyl 3 -methoxy-1-azabicyclo[3.2.0]hept-2-en-7-one-2-carboxylate (5.6 mg) as a clear oil: IR (CH₂ Cl₂) 1775 and 1700 cm⁻¹ ; UV (EtOAc) 288 nm; NMR (CDCl₃) δ2.87 (dd, 1, J=2.8 and 16, H6β), 3.03 (m, 2, H4a and H4b), 3.50 (dd, 1, J=5.5 and 16, H6α), 3.80 (m, 1, H5), 3.92 (s, 3, CH₃), 5.28 (s, 2, CH₂ φ), and 7.40 (m, 5, C₆ H₅); mass spectrum m/e 273 (M+) and 231 (M+-42).

This product is also obtained by treating the bicyclo keto ester with dimethyl sulfate and excess potassium carbonate in hexamethylphosphoramide or dimethylformamide.

EXAMPLE 25 Benzyl 3-phenylthio-1-azabicyclo[3.2.0]hept-2-en-7-one-2-carboxylate ##STR31##

An ice-cold solution of benzyl 1-azabicyclo[3.2.0]heptan-3,7-dione-2-carboxylate (13 mg, 0.05 mmol) in anhydrous acetonitrile is treated with N,N-diisopropylethylamine (10.4 μl, 0.06 mmol) and diphenyl chlorophosphate (10.9 μl, 0.053 mmol) and the resulting solution is stirred in the cold and under a nitrogen atmosphere for 90 mins. More N,N-diisopropylethylamine (8.7 μl, 0.05 mmol) and thiophenol (5.1 μl, 0.05 mmol) are added and the reaction mixture is stirred in the cold for 2 hours. The resulting mixture is combined with a second similar run, diluted with ethyl acetate to 10 ml volume, washed with water, 1 M pH3 phosphate buffer, 5% aqueous sodium bicarbonate, and brine, dried over magnesium sulfate, and evaporated under vacuum to an oil (34 mg). This material is purified on a 0.25 mm×20×20 silica gel GF plate using 3:1 toluene-ethyl acetate as developing solvent. The UV visible band at R_(f) 0.55 is removed and eluted with ethyl acetate. Evaporation of the solvent leaves a residue which is lyophilized from benzene to provide benzyl 3-phenylthio-1-azabicyclo[3.2.0]hept-2-en-7-one-2-carboxylate (17 mg) as an amorphous, white powder.

EXAMPLE 26 Preparation of Pharmceutical compositions

One such unit dosage form comprises 120 mg of sodium 1-azabicyclo[3.2.0]heptan-3,7-dione-2-carboxylate with 20 mg. of lactose and 5 mg of magnesium stearate and placing the 145 mg mixture into a No. 3 gelatin capsule. Similarly, by employing more of the active ingredient and less lactose, other dosage forms can be put up in No. 3 gelatin capsules and should it be necessary to mix more than 145 mg of ingredients together, larger capsules such as compressed tablets and pills can also be prepared. The following examples are illustrative of the preparation of pharmaceutical formulations:

    ______________________________________     TABLET              PER TABLET     ______________________________________     Sodium 1-azabicyclo[3.2.0]heptan-     3,7-dione-2-carboxylate                         125 mg.     Cornstarch, U.S.P.   6 mg.     Dicalcium Phosphate 192 mg.     Lactose, U.S.P.     190 mg.     ______________________________________

The active ingredient is blended with the dicalcium phosphate, lactose and about half of the cornstarch. The mixture is then granulated with a 15% cornstarch paste (6 mg) and rough-screened. It is dried at 45° C. and screened again through No. 16 screens. The balance of the cornstarch and the magnesium stearate is added and the mixture is compressed into tablets, approximately 0.5 inch in diameter each weighing 800 mg.

    ______________________________________     PARENTERAL SOLUTION     Ampoule:     Sodium 1-azabicyclo[3.2.0]heptan-     3,7-dione-2-carboxylate      500    mg.     OPTHALMIC SOLUTION     Sodium 1-azabicyclo[3.2.0]heptan-     3,7-dione-2-carboxylate      100    mg.     Hydroxypropylmethyl          5      mg.     Sterile Water       to       1      ml.     OTIC SOLUTION     Sodium 1-azabicyclo[3.2.0]heptan     3,7-dione-2-carboxylate      100    mg.     Benzalkonium chloride        0.1    mg.     Sterile Water       to       1      ml.     TOPICAL OINTMENT     Sodium 1-azabicyclo [3.2.0]heptan     3,7-dione-2-carboxylate      100    mg.     Polyethylene Glycol 4000U.S.P.                                  400    mg.     Polyethylene Glycol 400 U.S.P.                                  1.0    gram     ______________________________________

The active ingredient in the above formulations may be administered alone or in combination with other biologically active ingredients, as for example, with other antibacterial agents such as lincomycin, a penicillin, streptomycin, novobiocin, gentamicin, neomycin, colistin and kanamycin, or with other therapeutic agents such as probenecid. 

What is claimed is:
 1. A compound having the structure: ##STR32## wherein: R is hydrogen; an alkali, alkaline earth, or amine cation selected from the group consisting of: sodium, potassium, calcium, benzhydrylamine, N-benzyl-2-phenethylamine, N,N'-dibenzylethylenediamine, procaine; or an ester moiety selected from: methallyl, 3-methylbutenyl, 3-butenyl, methylthioethyl, benzyl, p-t-butylbenzyl, m-phenoxybenzyl, p-pivaloyloxy-benzyl, p-nitrobenzyl, pivaloyloxymethyl, 3-phthalidyl, acetoxymethyl, propionyloxymethyl, acetylthiomethyl, pivaloylthiomethyl, allyl, 4-butenyl, 2-butenyl, 3-methyl-2-butenyl, phenacyl, acetoxyacetylmethyl, methoxymethyl, p-acetoxybenzyl, p-pivaloyloxybenzyl, p-isopropoxybenzyl, 5-indanylmethyl, 5-indanyl, benzyloxymethyl, ethylthioethyl, methylthiopropyl, methoxycarbonyloxymethyl, ethoxycarbonyloxymethyl, dimethylaminoacetoxymethyl, crotonolacton-3-yl, and acetamidomethyl.
 2. An antibiotic pharmaceutical composition comprising a therapeutically effective amount of a compound according to claim 1 and a pharmaceutical carrier therefor. 